Kind of funny Big D, all I've been doing for the last 4/5 days when on the internet is trying to learn about PIDs, more specifically trying to find a nice one on US ebay to buy and then how I'd go about running it. Maybe over kill but I certainly love gadgets, and certainly enjoy educating myself about various bits and pieces like this so I'm still pretty keen to get one.
God this stuff (info) is so hard to find in Oz though. I've been looking at options for inputs and generally your looking at thermocouples, RTDs, Linear voltage inputs, and if your lucky you may be able to get a NTC thermistor input option as well. Well, the platnium RTDs sound pretty good but do you think I could find one in Oz with a price. Nope. So about a $100 buck, thanks Bigd for that one-guess I might give the RTD a miss, bummer.
I'm thinking if I go this option I'm either going to get a thermocouple from the ebay in the states or, if my research pans out I may be able to use an LM35 Precision Celcius Temperature Sensor (~$8), I may possibly need to build an ampilfier so the PID can use the input but it looks as though most PIDs may be able to direct read an LM35 producing 10mV/degree C.
Any of you guys care to give me your thoughts or share your knowledge in this aspect, particularly the use of an LM35 as direct input to a PID. I know there can be issues with using long leads to the LM35, so maybe a thermistor is another possibility (also dirt cheap

at about $2).
I think I'm going to end up building myself a digital thermometer or two using panel mounted digital voltmeters and three or more temp probes that I just select by using a switch, centring around the use of LM35's or thermistors. This comes after finding a couple of brewing sites talking about using thermistors in the brewery.
Cheers, Justin